Darkness in literature: The Dark is Rising by Susan Cooper

Reading Susan Cooper's gloriously Manichaean exploration of the dark through the life of 11-year-old Will Stanton is a Christmas ritual for me

'It was very dark by the time they left; the sky had not cleared, and no moon nor even a single star glimmered through the black night. The lantern that Robin carried cast a glittering circle of light on the snow ... ' Illustration from the Folio Society's new edition of The Dark is Rising by Laura Carlin Photograph: Folio Society

Susan Cooper's sequence of five children's stories, The Dark Is Rising, is, you'll have guessed, all about the dark. The dark as velvety, blanketing night. The dark as the keeper of mysteries, ineffable and unknowable. Above all, the dark as counterpoint to the light; as one side of the great battle between evil and good.

The Dark Is Rising is a Christmas ritual for me. The story starts on 20 December, and it is on 20 December each year that I start reading it. It is the night before Will Stanton's 11th birthday. All is happy anticipation and the busy, noisy stuff of a family coming together for the Christmas holiday. Will goes to bed with not much on his mind except a hope that his dearest birthday wish might be granted: deep, white, enfolding snow.

He puts out the light. And then the terror comes.

There's something extraordinary in the way Cooper describes this fear of the dark. It is a child's anxiety at the blank blackness redoubled; stretched to its extreme, because it quickly becomes clear that there is something more to Will's terror than can be explained away by an appeal to the everyday. It is, oddly, the moment when Will switches on his bedside lamp that is the most telling (and the most recognisable, perhaps, to any of us who have once been afraid of the dark): "The room was at once a cosy cave of yellow light, and he lay back in shame, feeling stupid." Then: "He switched off the light again, and instantly everything was even worse than before. The fear jumped at him for the third time like a great animal that had been waiting to spring. Will lay terrified, shaking, feeling himself shake, yet unable to move." For years I couldn't read this passage without feeling petrified myself, and making my own cosy cave of yellow light to stave off the terrors wrought by the imagination. It's all the more powerful because nothing really happens, beyond a skylight breaking under the weight of the beautiful, longed-for snow, and a rook's feather drifting in to Will's room ...

As the story goes on, it becomes clear that during this black night of fear some great change has been wrought in Will. But it is never fully explained what this feeling – "as if some huge weight were pushing at his mind, threatening, trying to take him over" – really means, or what, precisely, happens to him that night. What is clear is that when he steps out into the great white brightness of snowfall the next morning, he can work magic, and is one of the Old Ones, a fighter in the age-old battle against the Lords of the Dark. And yet he is still bound up in the warm happiness of carol singing and mince pies, and the bright promise of the tree and its presents. He is a young boy who shifts between high magic and and the utterly, comfortingly ordinary fact of a joyful family Christmas.